Good plans for a "modern" single cylinder?

[Cedge]

Apulin
Good luck with the student project, but you've obviously misread the nature of the local community. You've asked for proprietary drawings to be copied and that is a huge taboo here. As I recall, at least back in the bronze age of my own ancient educational experiences, a student was expected to design his own project rather than copying or piggybacking on other peoples already established works. Long and short.... sorry dude, but we're not here to augment your GPA by handing you a ready to build project.

We often help brainstorm, work around technical problems and lend high levels of moral support and encouragement, but only with those who are willing to do the required work themselves. I, for one, find your approach more than a little pretentious and quite negative in nature.

Steve

 

[Tin Falcon]

This is a hobby board. Folks that build and occasionally design engines for fun. A few here may sell engines or plans for profit.
If you are engineering student tasked with a design project then start designing. Do not expect anyone here to hand you a set of engine plans so you and your buds can enter a competition. Engineering is about problem solving.
You need to design and build. And if you want help I suggest you listen carefully to advise given.
Tin

 

[apullin]

Hrm, seems like some pretty harsh language being used.

You've asked for proprietary drawings to be copied and that is a huge taboo here.

I think you should re-read my post, and pay attention to the language. It's quite clear that I am asking if it is indeed "taboo" to ask for that set of plans, considering they are not even available for purchase. I didn't ask for someone to send me a copy; my conjecture was about the appropriateness of such an inquiry. It just seems that you're reacting to something that didn't even happen.

We often help brainstorm, work around technical problems and lend high levels of moral support and encouragement, but only with those who are willing to do the required work themselves. I, for one, find your approach more than a little pretentious and quite negative in nature.

While I did lead out my original post with a general call for "advice" and "recommendations", that was in the scope of the genesis of the post: searching for available sets of plans. Someone asked about the application, and I was more than happy to share, but I haven't solicited anyone to implement a solution for me. If anything, I've continually said, "starting point"

I'm not sure what part of it you count as pretentious.

sorry dude, but we're not here to augment your GPA by handing you a ready to build project.

This doesn't have anything to do with GPA. You assume far too much, and it reflects very poorly on you.

This is a hobby board. Folks that build and occasionally design engines for fun. A few here may sell engines or plans for profit.
If you are engineering student tasked with a design project then start designing. Do not expect anyone here to hand you a set of engine plans so you and your buds can enter a competition. Engineering is about problem solving.

I'm not even sure how to respond to this in a metered way; again, I think you've misread my words, and have taken me for some kind of a beggar or thief. I'd sure like to buy the plans, but if you look at the thread of the discussion, stemming from the initial reply, the issue is that the plans are not available for purchasing. I even say on the same line that I've seen there is some limited availability of the source material via eBay, and further ask if there would be alternate ways of getting a set of plans. I just don't know how to be more clear about it, really.

I urge you to compare the content of your reply to, say, the first reply in this thread. I ask about existing designs, and someone tells me about a design that exists. Your reply hasn't really brought us anything, except a judgmental, uncouth tone. I'm well aware that engineering is "about problem solving". I am trying to solve a problem here: finding a starting point in a large design space.

Apullin....have you built an engine before?

Several low temperature Stirling engines. And I've "built" engines in the sense of "assembling" car engines, but that's just nuts/bolts/minor fitment. I haven't fabricated an IC engine, hence the search for a starting point.

I think I'll just order those pushrod boxer plans from Germany, since they are readily available, and I'll post some details on what I come up with in 6 months or so.

 

[Tin Falcon]

Apullin:
You are correct; your first post is asking about recommendations on engine plans. It is hard to do that without the full picture - the basic who, what, when, where, why, etc. It was not stated until a later post why you looking for the plans. Introductions do help a lot here. You accuse us of assumptions but made little attempt to give us a clear picture of who you are and why you are here until we asked a lot of questions.

Clear communication is an engineering skill. Clear questions will more likely lead to clear answers.

If you can lose the defensive tone , listen and ask nicely for the help you need, we can likely help you. Butting heads with administrators and mods and senior memberswill not get you help.
Tin

 

[Iron Cat]

Well, Good MORNING!!

Apullin, I've just read through all the posts on this thread. I have to admit, I don't always agree with Tin Falcon - but his last post is right on the mark.

Right up front, folks here like to get to know each other. Since members use so many different 'handles', hail from all walks of life, and post from virtually every part of the globe, it's considered a simple courtesy. I saw more than one query to that regard, which repetition finally led to a few small bits of a picture of 'you'. Those random bits pulled together, weren't as concise as a single, opening intro - including a clear explanation of your needs and intents.

In the past, there HAVE been students who have come here, definitely expecting too much to be done FOR them. Unfortunately, in the wanderingness of your posts, even I can see where that could be inferred. Your last post claims it's not so with you, and I expect anyone reading it (including Tin) will breath / has breathed a sigh of relief. The more recent, and gradually more intense, posts that you decided needed a defensive response, would not have, had you been more clear from the beginning.

Can I make a suggestion, engineer-to-be? Try to create one organized, helpful request - with the who (that's YOU - a bit of a bio, please?), what, when, where, why, how stuff needed for an organized, helpful response. The folks on this board, especially amongst the "administrators and mods and senior members", are ALL ABOUT helping. If you choose to present yourself as ready-to-learn, I honestly think you will be pleased with the results.

My two cents worth, tooooooo early on a Wednesday morning .............. zzzzzzzzzzz

 

[steamer]

Iron Cat

Dale couldn't have said it better! ;D

 

[doc1955]

You say you want a starting point over and over so attached are a motor to use it's inthere some where just need to release it ;-)

View attachment STARTING_POINT.pdf

 

[Tin Falcon]

Doc I think this guy may need some help understanding what is in the box. before he tries to think outside.
We are here to help all that want to learn and put out some effort.
Tin

 

[Cedge]

Nothing said so far changed any of my perceptions of the situation. My comments are the same as I'd give to my own kid or grandkids. Sorry if they caused you discomfort.... it's one of those grandfather things.

Steve

 

[dalem9]

Hi all I am a newbe here,And I have read alot of the post for the last few months. I was almost afarid to ask a questions because of a post that I had read about someone who was looking for a fast and easy way to get some plans , I am not here to to have someone do all the work for me And would never ask that . By what I have read you guys really know your stuff.My dream in life is to build a live steam loc.And this I am doing .I am A self tought michinist I have only had metal shop in high school. I finely got the tools that I needing to achive this goal. I have been working on this engine for eight years . I need help on how to figure out the oriface size for my burner for I have changed the fuel from coal to butane . I have bought lots of books to try to figure this out but have not been able to as of yet.I am the guy who every one in the neightor hood comes to for help ,But I have no one to turn to ,so I am so very happy to have found this site Thanks Dale

 

[1Kenny]

Hi dalem9,

There are some really helpful guys in the Boiler section that should be able to help or get you in the right direction. Don't be afraid to ask. Some may bark like a dog, but they don't bite.

Kenny

 

[dalem9]

Thank you very much I will check out Dale

 

[steamer]

You say you want a starting point over and over so attached are a motor to use it's inthere some where just need to release it ;-)

There is no need for insults. lets all be civil please.

Dave

 

[mu38&Bg#]

I see. The main point I'm trying to make is a model engine design is not going to be anything like what you are after. If you've studied engine design, just get on with it. It really isn't an easy task. I've been studying engine design on my own for about 4 years now and the volumes of texts and papers available is incredible. You have to start somewhere, but I don't think a model engine design will help much. Model engines are first and foremost designed to be easy to produce. This limits the power output and efficiency. A model engine design will begin at maybe 500g/kWh what will yo do with that? The Honda GX35 is 360g/kWh. One more thing, most model plans are scarce on surface finish, surface treatment, and fit & clearance details. Google is your friend. There are plenty of sites for Eco Marathon teams some having quite detailed specs. The rest is up to you. Performance varies dramatically at Eco Marathon from 1000+km/l to 60km/l with a huge 20% difference from first to second place. How engine design and driving come together, I don't know.

I've been working on an engine design for a year now, for a model airplane type application. Having countless RC engines to look at, it was easy to see what technology is used. It's fairly simple. I wanted to see what was more state of the art for little engines and purchased a Honda GX25 and found a drastic difference in design. By looking at several existing engines I'm fairly confident what I came up with will work. If it were me, I'd start dry based on the existing teams data.

Which injector are you using? Or were you able to get the tiny Bosch just for Eco Marathon?

What are the basics design specs so far?


Having been on message boards for so long and even when I worked in the hobby industry where we sold electric motors, so many projects begin as "top secret" that it doesn't bother me. Ask the right questions and the details come out. If they want help, details are shared and normal discussion ensues. Sometimes the individual didn't know what they were doing. Other times it was an engineer just a bit outside his field. If they didn't want to share details you just move on.

For those that don't know US copyright law says a work is protected for 70 years after death of the author. Longer if the family chooses to extend it or less if they choose to forfeit.

Greg

 

[apullin]

Which injector are you using? Or were you able to get the tiny Bosch just for Eco Marathon?

I'm not familiar with the "tiny Bosch injector". The injector we, and a lot of other teams, use is a Keihin injector that flows around 33 cc/minute. This does work for the power ranges that we're looking at, but at fairly low duty cycle.
I've built an experimental injector based on that one, whereon I removed the orifice tip at the very end of the injector and put my own new end on, with a smaller orifice. The stock orifice has two 150 micron diameter holes in it, and I've been able to reliably make 30 micron diameter holes using the UV laser in my lab, so we should be able to trim the fuel flow way, way down. Flow testing is forthcoming.

What are the basics design specs so far?

I wasn't quite expecting to delve into design specifics in this thread, but I have your attention now, so I may as well. Of course, I understand that no "model engine" already has this feature set. I'm pretty long-winded, so this is going to be long.

The design specs are loose so far; the 35-50cc displacement is chosen based on power requirements and estimates of achievable power per displacement.
That being said, we know it'll be:
- 4-stroke
- air cooled
- gasoline burning
- throttled
- fuel injection (easy for me, granted necessary tuning)
- computer controlled TCI spark (easy for me)
- As many ball bearings as possible
- Electric start
- compactness / lightness
I've seen plenty of terrible e-start additions, and it's a classic example of how adding it afterwards is a lot of effort for mediocre results.

Overhead valve & cam are desired based on the significantly higher HP/liter that's been achieved with that configuration. I understand that this might be a red herring; I've considered that it might be "better" to have relatively low power/displacement, if higher thermal efficiency can be had in such a configuration. I can't fully optimize the design in a single shot, so ... that is being elided for now.

A desired feature would also be ... ease of construction, so once I produce all the CNC programs and jigs, I can easily spin off multiple copies of the engine.
I mean, making a cylinder should only take a few minutes of cutting time on CNC lathe. And the liners/sleeves could be directly finished to 25 micron concentricity! If I built a honing tool, I could probably even finish hone them right in the chuck.
Interestingly, I often hear scoffs when I say how I want to reduce this thing to a series of automated manufacturing steps, but I think there is a serious boon therein.

Targeted engine speeds are for a single stage transmission, but there's only so far that can be practically taken (~10:1 with a huge output sprocket). Building a reducer box directly into the engine would be a neat feature, I think. That nice mini T5 transmission would be great! But the complexity of that in and of itself is so huge.
I don't think adding an integral speed reducer will be hugely difficult.

As many ball bearings as possible; possibly even little end con-rod needle bearings. Every model engine I've looked at so far uses little end bushings.
Oiling system is to be determined, and I was hoping to learn something about that by looking at a myriad of engine designs on this scale. I've had some ideas about how to do it using just a slinger and a minimal sump, or possibly a pre-pressurized oil reservoir.
Sort of on that sub-topic: Jerry Howell's V-twin engine is specifically described, on his website, as "able to run all day long as a generator". That certainly hasn't seemed to be the design goal for a lot of other model engine projects (nothing wrong with that), which makes me want to compare his design to others, so I've ordered a set of plans for that, too.

A counter-balancer would be great, too, although I've not seen one on a model engine yet. And since I can only afford junky, old motorcycles, I've not even dismantled a real engine with a counter-balancer in it.

So, desired/concept:
- DFM, in the context of CNC
- Integral speed reducer
- counter-balancer
- solenoid compression release

I hope that gives some picture of what feature set I am hoping to achieve. A motivator for a "ground up" engine was that addition of these to existing commercial engines would be equivalently as time consuming and complex as just designing it in from the start, and that there can be great value in integration. Very often, people are aghast at the mention of EFI, and the complexities therein; having extensive electronics and programming knowledge, that part will not be the challenge. Lastly, I'm also interested in just because, well, I am interested in the hobby. I've always wanted to build model IC engine, and it just happens that I think this is a really salient application.

 

[steamer]

OK We have some substance to discuss. A well thought out argument also.

I can find nothing amiss with your logic. I will take your word on EFI. A fall back plan would be simple carburetor, but you know that already.

If efficiency and ball bearings are the main thrust, you may be able to use a simple splash lubrication system and forgo an oil pump, which can be fussy in smaller sizes. Getting oil up to an overhead cam may be a problem, but you could lay the engine down and let gravity help you there.
Specific power output will clearly have some bearing here.

What kind of environment is this engine going to run in?....in a lab or "down the road"
I would ditch exposed overhead rockers and pushrods if your going to get it dirty. This would apply to a mileage competition car as well, as dirt will always find a a way, especially with exposed, oily surfaces. Button the engine up with rocker covers ect

Getting prints of Jerry's engines would have been some advice I would have given. It's very mature of you to think of that, and act on that, on your own.

Am I to assume that your will use a simple clutch mechanism? If your chain driving , watch your overhung loads, not only on the shaft, but the engine/gearbox housing also.


Better. ;D



Regards, Dave

 

[Admiral_dk]

Forget about the balancer in such a small engine as there's no benefit and more friction loss. I can't say exactly where a balancer starts to help, but we're in the 150-200 cc area.

Likewise - I do not think that a small end needle bearing will do much difference with splash lubrication.

You can use the camchain to lift oil up into the cylinder head - it's been done on motorcycles.

Run the crankcase under heavy vacuum will lower the pumping losses quite considerable - use the exhaust to make it with a oneway valve.

I will not say it can't be done, but it will cost you a small fortune to make an engine anywhere near the quality of a Honda engine.

 

[bearcar1]

Adding flys**t to the pepper shaker....... I would certainly think that a toothed belt arrangement in the final drive would be of benefit over the usage of a chain and sprocket. It would be a lot fewer possible places for a mechanical failure to occur as well as not having to deal with lubrication factors. Especially in an exposed to elements environment. As for the valving, personally I would steer away from pushrods and rockers for some of the same reasons. EFI in my opinion would have huge advantages, probably the highest priority area to focus on would be the aspiration ducting and the overall frictional losses generated internally.

BC1
Jim

 

[steamer]

I would agree with the timing belt option for the reasons Bearcar1 has stated. Probably lighter in weight also.

However, It's been done in cars and motorcycles for years with chain and from a splash lubrication perspective, it could provide some useful oil transfer.

That decision would be one of those design trade offs you hear about... ;D

Dave

 

[apullin]

Steamer: You've made some good points there. Making a doubly supported output shaft should be straightforward and very worthwhile.
Valve train should/will be enclosed. That Nemitt engine *really* looks the part, since it already has that. Along the same lines, it has that copper tube running from the head to the case, which must have something to do with oiling, and thus, I'd really like to take a look at how the oiling system there is done; since they're not using the belt to lift oil up into the head, there must be something else ...

The nearest equivalent "modern" engine I've seen is maybe some engines by Schillings, although there's zero availability of plans, as far as I can tell.

The clutch is secret for now. There are rules in place that your clutch has to supposedly "completely disengage", but enforcement of that rule is lax.
Fallback is just to have the correct bushings to apply the commonly used types of clutches (machinery or go-kart). My estimates of the complexity of a 'custom' clutch system are that it would be as or more difficult than just a basic running engine.


I'd definitely like to use a timing belt. Tiny chains have been problematic, and doing a belt is seemingly pretty easy; forgiving alignment, plenty of parts available cheaply.

Aspiration/ducting will be an interesting issue, due to the aspect ratio of the intake pipe, due to the smallish diameter, so any length increases will quickly make it straw-like.

Admiral_dk: I gave thought to the balancer just for smoother running. The vehicles are often very light, so light that their lawnmower engines are 25% of the overall weight. Those things don't have counterbalancers, and the vibration of the whole system can be quite severe.
You really think that making an engine of any "quality" will be really expensive? It's just aluminum and bearings and such ... maybe a few bits of exotic 4000 series aluminum will be needed for the pistons. I suppose if I want to try and arrange to get them cylinder Nikasil plated or anything, that will start to cost for custom setups in someone else's shop.

The exhaust->vacuum idea is great, but as I understand it, you need a highly "tuned" exhaust to actually get that to work? But that should be an external part that can be made after-the-fact, and I'll check it with a vacuum gauge down the road somewhere. And intake-to-crankcase ventilation is explicitly disallowed, unfortunately.


A prof was was just today goading me into making a carbon-carbon composite block, cylinder, piston, and conrod.... phew, now that would be pretty challenging and expensive ...